Uncovering Molecular Mechanisms Underlying Cell-to-Cell Movement and Long-Distance Trafficking of Viruses in Plants

揭示植物细胞间运动和病毒远距离贩运的分子机制

• 批准号: RGPIN-2015-05117
• 负责人: Wang, Aiming
• 金额: $ 2.77万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=668050
• 关键词: Uncovering; Molecular; Mechanisms; Underlying; Cell

Plant viruses infect all major crops and cause economic losses of multibillion dollars worldwide each year. As obligate intracellular parasites, plant viruses can only multiply in their host plants. In order to establish a systemic infection, upon successful reproduction of progeny viruses in primarily infected cells, the nascent viral genome must spread locally to neighboring cells, termed cell-to-cell movement, and further move systemically to other parts of the plant, named long-distance movement. Cell-to-cell movement of viruses occurs through plasmodesmata (PD), a specialized intercellular organelle, unique to the plant kingdom. PD are structurally complex microchannels that cross the cell wall and establish cytoplasmic and endomembrane continuity between neighbouring cells. PD allow small molecules to diffuse between cells and regulate the intercellular trafficking of macromolecules or macromolecular complexes such as viral particles and ribonucleic protein complexes. Viral cell-to-cell movement through PD is an active process mediated by virus-encoded protein(s). Long-distance movement is the process by which the virus moves from the mesophyll via bundle sheath cells, phloem parenchyma, and companion cells into phloem sieve elements (SE) where they are translocated, and then unloaded at a remote site from which further infection will occur. Due to the complexity of PD and various types of cells involved in viral spread, the molecular mechanism of viral intercellular movement is poorly understood. Our recent studies have shown that plant potyviruses, the largest and most agricultural important group of known viruses, form a special structure at PD via the coordinated action of two viral proteins, e.g., CI and P3N-PIPO, to facilitate viral cell-to-cell movement. Our most recent genetic work has also demonstrated that (1) the coat protein (CP) is required for systemic spread of potyviruses; and (2) in addition to viral genome replication and cell-to-cell movement, the potyviral CI protein also plays a distinct, essential role in viral long-distance movement. In this proposal, we propose to further investigate the pathways recruited for the formation of conical structures at PD and how CI and CP are involved in viral systemic movement. We will also identify host gene products required in potyviral cell-to-cell and long-distance movement, and further characterize their functional roles. Therefore, this proposal will advance our knowledge of viral local and systemic spread and directly contribute to the development of novel antiviral strategies. Moreover, the results obtained from the proposed work will also help better understanding of essential cellular processes such as cell-to-cell and long-distance trafficking of macromolecular complexes in plants, and thus contribute to life science by advancing knowledge in fundamental cell and molecular biology.

植物病毒感染所有主要作物，每年在全世界造成数十亿美元的经济损失。作为专性细胞内寄生物，植物病毒只能在其宿主植物中繁殖。为了建立系统性感染，一旦子代病毒在最初感染的细胞中成功繁殖，新生病毒基因组必须局部扩散到邻近细胞，称为细胞到细胞的运动，并进一步系统地移动到植物的其他部分，称为长距离运动。病毒通过胞间连丝（plasmodesmata，PD）进行细胞间移动，PD是植物界特有的一种细胞间细胞器。PD是结构复杂的微通道，其穿过细胞壁并在相邻细胞之间建立细胞质和内膜连续性。PD允许小分子在细胞之间扩散，并调节大分子或大分子复合物（如病毒颗粒和核糖核酸蛋白复合物）的细胞间运输。病毒通过PD的细胞间移动是由病毒编码的蛋白质介导的主动过程。长距离移动是病毒从叶肉经由维管束鞘细胞、韧皮薄壁组织和伴细胞移动到韧皮部筛元件（SE）的过程，在那里它们被移位，然后卸载到远处，从那里进一步感染将发生。由于PD的复杂性和参与病毒传播的各种类型的细胞，病毒细胞间运动的分子机制知之甚少。我们最近的研究表明，植物马铃薯Y病毒是已知病毒中最大和最重要的农业群体，通过两种病毒蛋白的协调作用在PD处形成特殊结构，例如，C1和P3 N-PIP 0，以促进病毒细胞到细胞的移动。我们最近的遗传学工作还表明：（1）外壳蛋白（CP）是马铃薯Y病毒系统性传播所必需的;（2）除了病毒基因组复制和细胞间运动外，马铃薯Y病毒CI蛋白在病毒长距离运动中也起着独特的重要作用。在这个提议中，我们建议进一步研究在PD时形成锥形结构的途径，以及CI和CP如何参与病毒的全身运动。我们还将确定马铃薯Y病毒细胞间和长距离运动所需的宿主基因产物，并进一步表征其功能作用。因此，这一建议将推进我们对病毒局部和全身传播的认识，并直接有助于开发新的抗病毒策略。此外，从拟议的工作中获得的结果也将有助于更好地理解基本的细胞过程，如细胞到细胞和植物中大分子复合物的长距离运输，从而通过推进基础细胞和分子生物学知识为生命科学做出贡献。